Answer Posted / venkatesh a
NGR- Neutral ground resistor.
Used to limit the ground fault current.
If the Line voltage getting leakage or shorted with ground
then fault curretn will flow.
If it is High voltage system this fault current will be
very high (KAmps). So this much high value fault current
will demage the fault current sensing devices (relays).
This fault current will reach the transformer Neutral
through the Neutral earth pits.
By adding the NGR in between the Transformer neutral and
Neutral earth pit, resistance of the fault current path
getting increase.
we Know that, resistance is more then the (fault) current
flow will be less.
Then easy to sence. Normally resistance will be 12 to 15
ohms depends upon the setting made at relays.
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